Riebeckite Mineral Data

General Riebeckite Information

Chemical Formula:

[ ]Na2(Fe++3Fe+++2)Si8O22(OH)2

Composition:

Molecular Weight = 935.90 gm

Sodium 4.91 % Na 6.62 % Na₂O

Iron 29.84 % Fe 23.03 % FeO / 17.06 % Fe₂O₃

Silicon 24.01 % Si 51.36 % SiO₂

Hydrogen 0.22 % H 1.92 % H₂O

Oxygen 41.03 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Na₂Fe²⁺₃Fe³⁺₂(Si₈O₂₂)(OH)₂

Environment:

Magmatic and metamorphic rocks.

IMA Status:

Valid Species (Pre-IMA) 1888

Locality:

Socotra island, Indian Ocean, Yemen. Link to MinDat.org Location Data.

Name Origin:

Named after the German traveler, Emil Riebeck (1853-1885).

Name Pronunciation:

Riebeckite + Pronunciation

Synonym:

Crocidolite - asbestos form

ICSD 38218

PDF 19-1061

Riebeckite Image

Images:

Riebeckite

Comments: Grayish black, coniform, massive crystals of riebeckite.
Location: Cape Province, South Africa. Scale: 8x6 cm.
© Dave Barthelmy

Riebeckite Crystallography

Axial Ratios:

a:b:c =0.5412:1:0.2956

Cell Dimensions:

a = 9.769, b = 18.048, c = 5.335, Z = 2; beta = 103.6° V = 914.24 Den(Calc)= 3.40

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/m

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.72(1), 8.42(1), 3.09(0.8),

Physical Properties of Riebeckite

Cleavage:

{110} Perfect, {???} Perfect

Color:

Blue, Black, Dark green.

Density:

3.4

Diaphaneity:

Translucent to subtranslucent to opaque

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Fibrous - Crystals made up of fibers.

Habit:

Massive - Fibrous - Distinctly fibrous fine-grained forms.

Habit:

Striated - Parallel lines on crystal surface or cleavage face.

Hardness:

4 - Fluorite

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Silky

Magnetism:

Nonmagnetic

Streak:

greenish brown

Optical Properties of Riebeckite

Gladstone-Dale:

CI meas= 0.087 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.087 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2035,KPDmeas= 0.2035,KC= 0.223
Ncalc = 1.76

Optical Data:

Biaxial (-), a=1.68-1.698, b=1.683-1.7, g=1.685-1.706, bire=0.0050-0.0080, 2V(Calc)=62-78, 2V(Meas)=68-85. Dispersion strong, r < v.

Pleochroism (x):

greenish blue, deep blue, smoky green, yellow, or indigo blue.

Pleochroism (y):

grayish blue, light yellowish green, green, yellow, or deep violet blue.

Pleochroism (z):

yellowish brown, deep blue, violet blue, dark smoky green, or black.

Calculated Properties of Riebeckite

Electron Density:

Bulk Density (Electron Density)=3.33 gm/cc
note: Specific Gravity of Riebeckite =3.40 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Riebeckite= 9.88 barns/electron
U=PE_Riebeckite x rElectron Density= 32.88 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Riebeckite is Not Radioactive

Riebeckite Classification

Dana Class:

66.01.03c.05 (66)Inosilicate Double-Width Unbranched Chains, W=2

(66.01)with P=2 amphibole configuration

(66.01.03c)Group 4, the sodic amphiboles

66.01.03c.01 Glaucophane []Na2(Mg3Al2)Si8O22(OH)2 C 2/m 2/m

66.01.03c.02 Ferroglaucophane []Na2(Fe3Al2)Si8O22(OH)2 C 2/m 2/m

66.01.03c.03 Crossite? Na2(Mg,Fe)3(Al,Fe)2Si8O22(OH)2 C 2/m 2/m

66.01.03c.04 Magnesioriebeckite []Na2[(Mg,Fe)3Fe2]Si8O22(OH)2 C 2/m 2/m

66.01.03c.05 Riebeckite []Na2(Fe3Fe2)Si8O22(OH)2 C 2/m 2/m

66.01.03c.06 Eckermannite NaNa2(Mg4Al)Si8O22(OH)2 C 2/m 2/m

66.01.03c.07 Ferro-eckermannite NaNa2(Fe4Al)Si8O22(OH)2 C 2/m 2/m

66.01.03c.08 Magnesio-arfvedsonite NaNa2(Mg4Fe)Si8O22(OH)2 C 2/m 2/m

66.01.03c.09 Arfvedsonite NaNa2(Fe4Fe)Si8O22(OH)2 C 2/m 2/m

66.01.03c.09a Fluoro-magnesio-arfvedsonite! NaNa2(Mg,Fe)4Fe[Si8O22](F,OH)2 C 2/m 2/m

66.01.03c.09b Potassicarfvedsonite! KNa2Fe4FeSi8O22(OH)2 C 2/m 2/m

66.01.03c.10 Kozulite NaNa2Mn4(Fe,Al)Si8O22(OH)2 C 2/m 2/m

66.01.03c.11 Nyboite NaNa2(Mg3Al2)Si7AlO22(OH)2 C 2/m 2/m

66.01.03c.11a Ferronyboite! NaNa2(Fe)3Al2(Si7Al)O22(OH)2 C 2/m 2/m

66.01.03c.11b Ferric-ferronyboite! NaNa2(Fe)3(Fe)2(Si7Al)O22(OH)2 C 2/m 2/m

66.01.03c.11c Fluoronyboite! NaNa2(Al2Mg3)(Si7Al)O22(F,OH)2 C 2/m 2/m

66.01.03c.12 Leakeite NaNa2(Mg2Fe2Li)Si8O22(OH)2 C 2/m 2/m

66.01.03c.12a Ferroleakeite! NaNa2(Fe)3(Fe)2Li(Si8O22)(OH)2 C 2/m 2/m

66.01.03c.12b Potassicleakeite! KNa2Mg2Fe2LiSi8O22(OH)2 C 2/m 2/m

66.01.03c.13 Kornite Na(CaNa)Fe4(Al,Fe)Si7AlO22(OH)2 C 2/m 2/m

66.01.03c.14 Ungarettiite NaNa2(Mn2Mn3)Si8O22O2 C 2/m 2/m

66.01.03c.15 Fluoro-ferroleakeite NaNa2(Fe2Fe2Li)Si8O22F2 C 2/m 2/m

66.01.03c.16 Obertiite! NaNa2(Mg3FeTi)Si8O22(O,F,OH)2 C 2/m 2/m

66.01.03c.17 Dellaventuraite! NaNa2(Mg2,Mn,Li,Ti)Si8O22O2 C 2/m 2/m

Strunz Class:

09.DE.25 09 - SILICATES (Germanates)

09.D - Inosilicates* Structural terminology according to Liebau (1985)

09.DE -Inosilicates with 2-periodic double chains, Si4O11; amphibole family

09.DE.25 Arfvedsonite NaNa2(Fe4Fe)Si8O22(OH)2 C 2/m 2/m

09.DE.25 Ferroglaucophane []Na2(Fe3Al2)Si8O22(OH)2 C 2/m 2/m

09.DE.25 Crossite? Na2(Mg,Fe)3(Al,Fe)2Si8O22(OH)2 C 2/m 2/m

09.DE.25 Eckermannite NaNa2(Mg4Al)Si8O22(OH)2 C 2/m 2/m

09.DE.25 Glaucophane []Na2(Mg3Al2)Si8O22(OH)2 C 2/m 2/m

09.DE.25 Fluoro-ferroleakeite NaNa2(Fe2Fe2Li)Si8O22F2 C 2/m 2/m

09.DE.25 Ferro-eckermannite NaNa2(Fe4Al)Si8O22(OH)2 C 2/m 2/m

09.DE.25 Ferroleakeite! NaNa2(Fe)3(Fe)2Li(Si8O22)(OH)2 C 2/m 2/m

09.DE.25 Ferronyboite! NaNa2(Fe)3Al2(Si7Al)O22(OH)2 C 2/m 2/m

09.DE.25 Ferric-ferronyboite! NaNa2(Fe)3(Fe)2(Si7Al)O22(OH)2 C 2/m 2/m

09.DE.25 Obertiite! NaNa2(Mg3FeTi)Si8O22(O,F,OH)2 C 2/m 2/m

09.DE.25 Nyboite NaNa2(Mg3Al2)Si7AlO22(OH)2 C 2/m 2/m

09.DE.25 Magnesioriebeckite []Na2[(Mg,Fe)3Fe2]Si8O22(OH)2 C 2/m 2/m

09.DE.25 Kozulite NaNa2Mn4(Fe,Al)Si8O22(OH)2 C 2/m 2/m

09.DE.25 Kornite Na(CaNa)Fe4(Al,Fe)Si7AlO22(OH)2 C 2/m 2/m

09.DE.25 Leakeite NaNa2(Mg2Fe2Li)Si8O22(OH)2 C 2/m 2/m

09.DE.25 Magnesio-arfvedsonite NaNa2(Mg4Fe)Si8O22(OH)2 C 2/m 2/m

09.DE.25 Ungarettiite NaNa2(Mn2Mn3)Si8O22O2 C 2/m 2/m

09.DE.25 Riebeckite []Na2(Fe3Fe2)Si8O22(OH)2 C 2/m 2/m

09.DE.25 Potassicleakeite! KNa2Mg2Fe2LiSi8O22(OH)2 C 2/m 2/m

09.DE.25 Fluoronyboite! NaNa2(Al2Mg3)(Si7Al)O22(F,OH)2 C 2/m 2/m

09.DE.25 Fluoro-magnesio-arfvedsonite! NaNa2(Mg,Fe)4Fe[Si8O22](F,OH)2 C 2/m 2/m

09.DE.25 Potassicarfvedsonite! KNa2Fe4FeSi8O22(OH)2 C 2/m 2/m

09.DE.25 Dellaventuraite! NaNa2(Mg2,Mn,Li,Ti)Si8O22O2 C 2/m 2/m

Other Riebeckite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

See Also:

Links to other databases for Riebeckite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Amethyst Galleries' Mineral Gallery
5 - Athena
6 - EUROmin Project
7 - Ecole des Mines de Paris
8 - GeoScienceWorld
9 - Glendale Community College
10 - Google Images
11 - Google Scholar
12 - Handbook of Mineralogy (MinSocAm)
13 - Handbook of Mineralogy (UofA)
14 - HyperPhysics
15 - MinDAT
16 - Mineralienatlas (Deutsch)
17 - Online Mineral Museum
18 - QUT Mineral Atlas
19 - Ruff.Info
20 - Scandinavian mineral gallery
21 - WWW-MINCRYST

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Print or Cut-and-Paste your Riebeckite Specimen Label here :

Riebeckite

[ ]Na2(Fe++3Fe+++2)Si8O22(OH)2
Dana No: 66.01.03c.05 Strunz No: 09.DE.25
Locality:

Notes:

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